The function of different immunopathologic mechanism in diseases of the eye is presently incompletely understood. Distinct local and/or systemic cellular and humorol mechanisms may have significantly different roles, either alone or in concert with other mechanisms, in causing ocular inflammation and damage to vital ocular structures, and in controlling infectious agents in the eye. An understanding of the separate and collective roles of different immunopathologic mechanisms in ocular inflammatory disease will be of great value towards the ultimate goal of separating protective from damaging effects of immune responsesl in the eye. Such responses are the cause of a substantial proporition of blindness world-wide. The present studies will concentrate on the roles of IgE antibody-mediated mechanisms, mast cells and eosinophils in ocular immunopathology in three model systems: 1. guinea pigs infected intraocularly or systemically with larvae of Toxocara canis, Ascaris suum, Onchocerca cervicalis or Onchocerca gutturosa or immunized with antigens capable of inducing high-tier IgE antibodies; 2. rats immunized with the above parasites and antigens; 3. Atopic dogs with spontaneous hypersensitivity and circulating IgE antibodies to environmental antigens. A model for human atopic vernal conjunctivitis will be sought. IgE antibodies in serum, tears, and ocular fluids will be measured by the passive anaphylactic (P-K) reaction and by radioimmunoassay. IgE-producing plasma cells will be demonstrated by immunofluorescent microscopy. Mast cell degranulation and eosinophil activation will be studied by electron microscopy. Ocular and periocular IgE production will be studied in actively and passively immunized animals and after adoptive transfer of IgE-producing cells. The ability of specific and nonspecific inflammatory reactions to promote ocular IgE responses, and of IgE-mediated reaction to influence other immunopathologic process will be examined. The role of eosinophils, eosinophil granules and eosinophil mediators in causing retinal degeneration and conjunctival changes will be defined with eosinophils isolated from the anterior chambers of guinea pigs infected with ascarid larvae. The ability of eosinophils to damage parasites will be studied in tissue culture. A diagnostic test based on the demonstration of intraocular T. canis antigen will be developed.